Vol 42, No 3 (2016)

In the paper, methods of classification of signal sources in cognitive radio systems that are based on artificial neural networks are discussed. A novel method for improving noise immunity of RBF networks is suggested. It is based on introducing an additional self-organizing layer of neurons, which ensures automatic selection of variances of basis functions and a significant reduction of the network dimension. It is shown that the use of auto-associative networks in the problem of the classification of sources of signals makes it possible to minimize the feature space without significant deterioration of its separation properties.

In this work we discuss usage of expression templates with features of modern C++ language standards. We give an evaluation model for expression templates that accounts for requirements of operator implementation functions. An algorithm for evaluation of expression templates in this model is presented with proof of its optimality. In conclusion we describe implementation methods that are necessary for implementing this algorithm on modern compilers.

This paper presents an improvement of an effort estimation method that can be used to predict the level of effort for software development projects. A new estimation approach based on a two-phase algorithm is used. In the first phase, we apply a calculation based on use case points (UCPs). In the second phase, we add correction values (a₁, a₂) obtained via least squares regression. This approach employs historical project data to refine the estimate. By applying the least squares regression approach, the algorithm filters out estimation errors caused by human factors and company practice.

A technology of the deterministic replay of an execution process in virtual machines can be used for debugging, improving reliability and robustness, software development and incident investigation (including reverse engineering of malware). The paper describes an implementation of deterministic replay for guest machines based on IA-32 in the emulator QEMU. This implementation minimizes the list of replayed devices. The organization of QEMU is discussed in detail, and the techniques used in the implementation are thoroughly explained. The key performance characteristics, such as the size of log of nondeterministic events and slowdown are experimentally measured.